Mammaliaformes Rowe 1988
   [crown] Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theriiformes Rowe, 1988 see Division Theriiformes Rowe, 1988
       Infraclass Holotheria Wible, Rougier, Novacek, McKenna & Dashzeveg, 1995 see Clade Holotheria Wible, Rougier, Novacek, McKenna & Dashzeveg 1995
         Superlegion Trechnotheria McKenna, 1975 see Clade Trechnotheria McKenna 1975
           Legion Cladotheria McKenna, 1975 see Clade Cladotheria McKenna 1975
             Sublegion Zatheria McKenna, 1975 see Clade Zatheria McKenna 1975
               Infralegion Tribosphenida McKenna, 1975 see Subclass Boreosphenida Luo, Cifelli & Kielan-Jaworowska, 2001
                 [crown] Supercohort Theria Parker & Haswell, 1897 - therians see Subclass Theria Parker & Haswell, 1897
                   Cohort Marsupialia Jameson, 1818 - marsupials
                     Magnorder Ameridelphia Szalay, 1982 see Clade Ameridelphia Szalay 1982
                       Order Didelphimorphia Gill, 1872
                         Family Didelphidae Gray, 1821 - American opossums
                           Subfamily Didelphinae Gray, 1821
                             Tribe Monodelphini Talice, de Mosera & Machado, 1960
                               Subtribe †Zygolestina Marshall, 1987
                                 Genus †Zygolestes Ameghino, 1898